Princess Diana Biographer Claims in New Special She Was at 'Her Wit's End' When She Made Secret Recordings

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Author Andrew Morton says it was very important to Princess Diana that the public know her side of the story.

Morton penned the 1992 biography Diana: Her True Story that was based on the secret recorded conversations between Princess Diana and her friend, James Colthurst, prior to her divorce from Prince Charles in 1996. "She was at her wit's end," Morton claims in this sneak peak of the three-hour special Princess Diana: Tragedy or Treason?, on TLC. "So, what she wanted to do was tell her story, her side of the story, because, as it were, [she'd] been made a prisoner inside the palace for 10 years."

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Morton also explains why he and the publishing company kept Diana "an anonymous source for her own story" when the book was first published. "We wanted to give Diana deniability," he says. "That is to say when she's asked by the Queen or Prince Philip, 'Did you speak to Andrew Morton?,' she could look them in the eye and say, 'No, I did not.'"

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Morton recalls being in disbelief upon first hearing Princess Diana's recordings, which included her talking about Prince Charles' alleged affair with his now-wife, Camila Parker Bowles. "I was listening to Diana talk about her eating disorder, her suicide attempts, about this woman called Camila," he remembers. "It was like listening to someone who had been kept inside a prison, who just blurted out their story. She was trying to make sense of it. She was trying to move forward. She was reaching, seeing some kind of light at the end of the tunnel."

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Earlier this year, the biography was republished, timed to the 20th anniversary of Princess Diana’s death in August, and includes transcripts of Princess Diana's conversations with Colthurst. "When I go into the palace for a garden party... I am a very different person," Princess Diana says in an excerpt from the transcripts, which is read by a voice actress in the TLC special. "I conform to what's expected of me when I am in their presence. I do as I'm expected. What they say behind my back is none of my business, but I come back here and I know when I turn my light off at night, I did my best."

Princess Diana: Tragedy or Treason? airs Monday, July 31, on TLC.

WATCH: Prince William Says He Wishes Princess Diana Could Have 'Seen the Children Grow Up'

In addition to the TLC special, Prince Harry and Prince William also gave their first-ever joint interview for HBO's documentary Diana, Our Mother: Her Life and Legacy. Check out what the royals had to say about their mother's whirlwind life, including how she became the "people's princess" and her lasting impact years beyond her tragic death.

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